Conventionally, there are used a lot of vibration-damping polymer materials utilizing polymer viscoelastic behavior for reducing vibration of metals and the like. Since a vibration-damping material is usually used in the state that it is adhered to a hard substrate such as a metal, acrylic resin-based vibration-damping materials excellent in adhesion have been investigated frequently. For example, JP-A No. 4-202586 discloses a cross-linkable copolymer made of 75 to 92% by weight of a monomer necessarily composed of an alkyl acrylate having C8-12 alkyl group and 8 to 25% by weight of a carboxyl group-containing monomer which a polymer obtained by homo-polymerization of this monomer has a glass transition temperature of 50° C. or more.
Recently, vibration-damping materials are variedly used, and it is required to have various abilities such as transparency, rigidity, impact resistance and weather resistance in addition to conventional vibration-damping property. Particularly, an acrylic resin-based vibration-damping material is often required to have flame retardancy, and it is desired to achieve a vibration-damping materials having both vibration-damping property and flame retardancy.
Usually, the flame retardancy of resin is imparted by blending a flame retarder. In a general method, an organic flame retarder such as phosphorus-based retarders, nitrogen-based retarders and halogen-based retarders, and an inorganic flame retarder such as antimony trioxide and aluminum hydroxide are used as the flame retarder, and these are blended in the resin. However, when a large amount of flame retarder is added for enhancing flame retardancy, problems should occur, for example, that a flame retarder bleeds onto the surface of the resin to deteriorate transparency, and that the other properties such as mechanical strength are remarkably reduced. Further, when a halide is used as the flame retarder, toxicity thereof is problematical. There are various investigation for solving these problems, and for example, JP-A No. 7-82324 discloses a copolymer made of a monomer which can produce a transparent polymer when polymerized singly, and a monomer having a polymerizable unsaturated double bond containing phosphorus.
However, the copolymer disclosed in JP-A No. 7-82324 is a hard material used mainly for grazing, and the material cannot be applied to uses requiring flame retardancy and vibration-damping property simultaneously.